It’s the oldest rule in politics: If you ever find yourself with a double-digit lead over all of your rivals, start accusing U.S. allies of knocking down the TwinTowers.

Did I type oldest? I meant the newest. On Wednesday, a series of polls showed Donald Trump head and shoulders above the rest of the GOP field both nationally and in this Saturday’s primary in the Palmetto State. To protect his lead, the former reality star decided to take his heresies against the Republican Party’s narrative on 9/11 one stepfarther.

“Who blew up the World Trade Center? It wasn’t the Iraqis, it was Saudi — take a look at Saudi Arabia, open the documents,” Trump told the gang at Fox & Friends Wednesday morning, after defending his bizarre theory that George W. Bush was president on September11.

Trump appeared to be referencing the 28 pages that were redacted from the 2002 Joint Inquiry into the 9/11 attacks. Those pages are widely said to implicate Saudi elites of financing the attacks. Last year, Massachusetts congressman Stephen Lynch told The New Yorker that the document offers direct evidence of “complicity on the part of certain Saudi individuals and entities in Al Qaeda’s attack onAmerica.”

The Donald reiterated his suspicion of Saudi involvement at a campaign event later in the day, Mediaitereports.

“It wasn’t the Iraqis that knocked down the World Trade Center,” Trump told a crowd in Bluffton, South Carolina. “It wasn’t the Iraqis. You will find out who really knocked down the World Trade Center, ‘cuz they have papers in there that are very secret. You may find it’s the Saudis, okay? But you will findout.”

Fifteen of the 19 hijackers were Saudi nationals. And in 2012, former senator Bob Graham of Florida, who headed the 9/11 inquiry, wrote in an affidavit, “I am convinced that there was a direct line between at least some of the terrorists who carried out the September 11th attacks and the government of SaudiArabia.”

Graham’s statement doesn’t constitute a claim that the Saudi royal family had foreknowledge of the attacks. But it is a strong suggestion that some Saudi elites were sympathetic enough to Osama bin Laden’s cause to help fund it. If Trump intended to claim that Saudi Arabia was more complicit in 9/11 than Saddam Hussein was, his point would be inarguable. But no matter what he meant, it’s not every day that someone with a solid chance of becoming our next president repeatedly accuses an American ally of complicity in the worst terrorist attack in U.S.history.